Penicillins

ABSTRACT

New penicillins and their salts and esters particularly active against Gram-negative organisms such as Pseudomonas spp., and their preparation and administration. The penicillins are active against clinically important organisms against which well-known broad spectrum penicillins are inactive and may generally be designated as aminoacyldipeptide penicillins of unusual structure and properties.

United States Patent Ferres et al.

Dec. 2, 1975 PENICILLINS Inventors: Harry Ferres, Horsham; Adrian Victor Kemmenoe, Westcott; Desmond John Best, Sutton, all of England Assignee: Bayer Aktiengesellschaft, Germany Filed: May 3, 1974 Appl. No.: 466,814

Foreign Application Priority Data May 4, 1973 United Kingdom 21203/73 US. Cl 260/239.1; 424/27l Int. Cl. C07D 499/44 Field of Search 260/239.1

[56] References Cited UNITED STATES PATENTS 3,340,252 9/1967 Alburn ct a] 260/239.l 3,483,188 12/1969 McGr'egor 260/239.l

Primary Examiner-Gerald A. Schwartz [57] ABSTRACT 15 Claims, N0 Drawings PENICILLINS This invention relates to penicillins which have, in general, a broad spectrum of antibacterial activity, being active against many species of Gram-positive and Gram-negative bacteria. They are thus useful as therapeutic (and, to a lesser extent, propylactic) agents in animals, including man and poultry. The invention further relates to methods for the preparations of these penicillins and to their use in therapy.

Although there are now available a number of semisynthetic penicillins having what is known as broadspectrum activity, no single penicillin is yet available which has a clinically useful level of antibacterial activity against all the pathogenic organisms encountered in clinical practice. The search thus continues for broadspectrum penicillins which have advantages, either in improved antibacterial effectiveness or wider spectrum of activity, over the available penicillins.

According to the present invention there is provided a penicillin of formula (I) or a pharmaceutically acceptable salt or ester thereof:

R is phenyl, phenyl substituted by one or more functional groups selected from hydroxy, halogen, nitro, alkoxy containing from 1 to 3 carbon atoms, and amino groups, 2- or 3- thienyl, cycloalkyl having from 3 to 7 carbon atoms, cycloalkenyl having from 5 to 7 carbon atoms or alkyl having from 1 to 4 carbon atoms;

R is hydrogen or an alkylgroup having from 1 to 3 carbon atoms; R is hydrogen or an organic radical containing up to 20 carbon atoms;

R is a group of formula (II) or (III):

C-R" (II) (III) wherein R is amino, monoor di-alkylamino wherein the alkyl groups contain from 1 to 4 carbon atoms, cyclohexylamino, hydrogen, alkyl having from 1 to 4 carbon atoms, or phenyl and R is amino or monoor dialkylamino wherein the alkyl groups contain from 1 to 4 carbon atoms, or cyclohexylamino.

The group R may be, for example, phenyl, 4-hydroxyphenyl, 3-chloro-4-hydroxyphenyl, 4-nitrophenyl, 4- chlorophenyl, 4-fluorophenyl, 4-methoxy-phenyl, 4- aminophenyl, 2-thienyl, 3-thienyl, cyclopropyl, cyclohexyl, cyclohexa-l,4dienyl, iso-propyl or methyl.

The group R may, for example, be hydrogen, phenyl, 4-hydroxyphenyl, 4-nitrophenyl, 4-chlorophenyl, 4- fluorophenyl, 4-methoxyphenyl, 4-aminophenyl, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, methoxy, ethoxy, n-propoxy, isopropoxy, methylene, ethylene, ethylthio, n-propoxy-methyl, carbamyl, carbamylmethyl, acetoxy, phenoxy, benzyloxy, Z-thienyl, 3-thienyl, indol-3-yl, lH-imidazol-S-yl, cyclohexa-l,4-dienyl, cyclopropyl or cyclohexyl.

The group R may, for example, be amino, methylamino, n-butylamino, tert-butylamino, cyclohexylamino, hydrogen, methyl, ethyl, nor iso-propyl, n-, secflor tert-butyl, or phenyl.

The group R may, for example, be amino, methylamino, dimethylamino, ethylamino, diethylamino, n-propylamino, iso-propylamino, tert-butylamino, nbutylamino or cyclophexylamino.

Preferably R is phenyl, 4-hydroxyphenyl, or 3-thienyl.

Preferably R is phenyl, 4-hydroxyphenyl, 4- chlorophenyl, 4-fluorophenyl, 4-nitrophenyl, 3-indolyl, or methylthiomethyl.

Preferably R is hydrogen.

Preferably R is amino or hydrogen.

Preferably R is amino.

Preferably the carbon atom to which the group R in formula (I) is attached is in the D configuration.

Preferably the carbon atom to which the group R in formula (I) is attached is in the D configuration.

Examples of suitable salts of compounds (I) include the sodium, potassium, calcium, magnesium or aluminium salts, and ammonium or substituted ammonium salts, for example those with trialkylamines such as triethylamine, procaine, dibenzylamine, triethanolamine, l-ephenamine, ethylpiperidine, and other amines which have been used to form salts with benzylpenicillins. In the case of compounds (I) which contain a basic nitrogen site in the side chain, acid addition salts may also be formed. Such salts include, for example, inorganic salts such as the sulphate, nitrate, phosphate, borate, thiocyanate, and hydrohalides, e.g. hydrochloride, hydrobromide and hydroiodide, and organic salts such as the acetate, oxalate, tartrate, malate, citrate, succinate, benz oate, ascorbate and methanesulphonate.

Examples of suitable pharmaceutically acceptable esters include those which break down readily in the human body to leave the parent acid, e.g. acyloxyalkyl esters such as acetoxymethyl, pivaloyloxymethyl, aacetoxyethyl, a-acetoxybenzyl and a-pivaloyloxymethyl esters, and alkoxycarbonylalkyl esters such as methoxy carbonyloxymethyl esters. Other suitable esters of this readily hydrolysable type include lactone, thiolactone, and dithiolactone esters (Le. compounds of formula (I) wherein the 3-carboxy group is esterified to produce a grouping of formula:

wherein X and Y are oxygen or sulphur and Z is a divalent hydrocarbon group), especially the phthalidyl and substituted phthalidyl esters e.g. 5,6-dimethoxyphthalidyl ester.

The compounds of this invention may be prepared by reacting 6-aminopenicillanic acid or a salt, ester or silyl derivative thereof with an N-acylating derivative of an acid of formula (IV) in which any reactive substituents may be blocked, wherein R, R, R and R are as defined in formula (I) and then, if necessary, carrying out one or more of the following steps (i) removing any silyl groups by hydrolysis or alcoholysis, (ii) converting an ester compound to a free acid or salt (iii) converting a salt to a free acid or a free acid to a salt (iv) removing any blocking groups to release the desired functional substituent (v) converting a free acid compound to an ester compound.

By the term silyl derivative used in connection with 6-aminopenicillanic acid (6-APA) we mean the product of the reaction between 6-APA and a silylating agent such as a halotrialkylsilane, halodialkylsilane, a halotrialkoxysilane, a dihalodialkoxysilane or a corresponding aryl or aralkyl silane and compounds such as hexamethyldisilazane. In general, halotrialkylsilanes are preferred, especially trimethylchlorosilane.

A reactive N-acylating derivative of the acid (IV) is employed in the above process. The choice of reactive derivative will of course be influenced by the chemical nature of the substituents in the acid. Thus, when the acid contains only acid stable groups, an acid halide is a suitable N-acylating derivative, preferably the acid chloride.

Such reagents would, however, be avoided when an acid labile group was present in the acid (IV). In such cases a suitable N-acylating derivative is a mixed anhydride. For this purpose particularly convenient mixed anhydrides are the alkoxyformic anhydrides.

However, with both the acid chloride and mixed anhydride N-acylating agents we have found that some racemisation may take place. To minimise such unwanted racemisation, we prefer to use an activated ester as the N-acylating agent. Such activated esters, for example the ester formed with l-hydroxybenzotriazole or, preferably, N-hydroxysuccinimide, may be prepared in situ by the reaction of the acid with the appropriate hydroxy compound in the presence of a carbodiimide, preferably dicyclohexylcarbodiimide.

Other reactive N-acylating derivatives of the acid (II) include the reactive intermediate formed by reaction in situ with a carbodiimide or carbonyldiimidazole, but the literature on the preparation of semisynthetic penicillins contains examples of other reactive Nacylating derivatives of acids suitable for coupling to 6-APA.

It will be understood, of course, that where a free acid of type (I) or a salt thereof is desired, it may be convenient to carry out the acylation reaction using an ester of 6-APA, and then to remove the ester group. Vice versa, if an ester is required, it may be convenient to carry out the acylation reaction using 6-APA or a salt thereof and thereafter to esterify the free acid.

R-Cd-CO-NH 3 CH3 (v) 2 coon wherein R is as defined in formula (I) and in which any reactive substituents may be blocked, with an N-acylating derivative of an acid of formula (VI) wherein R, R and R are as defined in formula (I), and if necessary, carrying out one or more of the following steps (i) removing any silyl groups by hydrolysis or alcoholysis, (ii) converting an ester compound to a free acid or salt thereof (iii) convertinga salt to a free acid or a free acid to a salt (iv) removing any blocking groups to release the desired functional substituents (v) converting a free acid compound to an ester compound.

The remarks made earlier with respect to silyl derivatives, N-acylating derivatives, and blocking groups, also apply to this process.

The compounds of this invention wherein R is a group of formula (II) may also be prepared by reacting a compound of formula (VII) or a salt, ester of silyl derivative thereof: 1

s on I 71 3 II) NH CH I i 5 l 0 coon c0 1 l H -CH2 E: m

wherein R, R, R and R are as defined in formula (I) and wherein any reactive substituents may be blocked, with cyanate ion, a C 4 alkyl isocyanate, cyclohexyl isocyanate, a formylating agent or an N-acylating derivative of an acid R COOI-I wherein R phenyl or an alkyl group having from I to 4 carbon atoms, followed, if necessary, by one or more of the following steps (i) re moving any silyl groups by alcoholysis or hydrolysis, (ii) converting an ester compound to a free acid or salt thereof, (iii) converting a salt to a free acid or a free acid to a salt (iv) removing any blocking groups to re lease the desired functional substituent, (v) converting a free acid compound to an ester compound.

It will be noted that the above process essentially consists in generating the desired group R from the free amino group in compound (VII). The reaction of amino compounds with cyanate ion and isocyanates to produce ureas and substituted ureas is well known. Likewise the formylation of amino compounds (e.g. using formic acid and acetic anhydride) is well known. Similarly, the acylation of amino compounds is extremely well known, and suitable N-acylating derivatives of acids have been discussed hereinbefore.

The compounds of this invention are broad spectrum penicillins, i.e. penicillins which not only have activity against Gram-positive bacteria, but also against a number of clinically important Gram-negative ORGAN- ISMS. The preferred compounds of this invention are active against such important organisms as Pseudomonas spp. against which the most well known broadspectrum penicillin (6[(D)a-aminophenylacetamido1- penicillanic acid ampicillin) is normally inactive. Moreover the preferred compounds of this invention are about as active as 6[(D)a-carboxy-3- thienylacetamido] penicillanic acid against Pseudomo nas spp., this latter compound being the most active of the known penicillins against those organisms.

Several of the preferred compounds of this invention have minimum inhibitory concentrations of from 5 12.5 ug/ml against some B-lactamase producing strains oof staphylococci, against which the majority of known broad spectrum penicillins are only marginally effective. The preferred compounds of this invention are not greatly serum-bound, and are not markedly inactivated by serum.

The penicillins of this invention show the characteristic lack of toxicity of penicillins generally. They may be administered by parenteral injection. The daily dose will depend on the identity of the penicillin and severity of infection. With the preferred compounds of this invention, a suitable average daily dose for an adult would be in the range of I00 to 5000mg. An average,

single dose for an adult would be from 20 to 500 mg.

The following Examples illustrate the preparation of some of the compounds of this invention:

In the following Examples amoxyc illin is the approved name for 6[D-a-amino-p-hydroxyphenylacetamido]penicillanic acid and ampicillin is the approved name for 6[D-a-aminophenylacetamido] penicillanic acid. Epicillin is the approved name for [D- a-amino -cyclohexa-l,4,-dienylacetamido]penicillanic acid. All temperatures are in C. All biochromatograms were run in butanol/ethanol/water. All compounds were made by one of the following generally applicable methods.

The majority of the starting materials used in the following Examples are known. However, the following literature references describe generally applicable methods which may be used to prepare the starting materials:

UREIDO-ACIDS DAKIN: AmenChemJ. 44 54 ANDREASCI-I: Monats. 23. 805

NEVILLE, MGEE: Can.J.Chem. 4I, 2I23-9 (I963) WIELAND: Biol. 38, 389, Ann.3.

DAVIS, BLANCHARD: J.Amer.Chem.Soc. SI, I797 LEUTHARDTBRUNNER: Helv.Chim.Acta. 30, 964-5 SUBSTITUTED UREIDO-ACIDS BALL, SKINNER, SHIVE: Texas Rept. Biol.Med. 21(2) BRITISH PATENTS l30l96l/2. GUANIDINO-ACIDS KAPFHAMMER, MILLER: Z. Physiol,Chem. 225, l-I2,

RADKA PANT: Ibid 335, 272-(1964) FRAMM, KAPELLER: Arm. (I925) 442, I44

HABEL: Can.J.Biochem. Physiol. 38, 493

RAMSAY: Ber. 41, 4390 FORMAMlDO-ACIDS SHEEHAN, YOUNG: J.Amer.Chem.Soc. (I958), 80,

METHOD A A solution of the guanidino-acid, hydrochloride (5m. mole) in dry dimethylformamide (5 ml) was added over 10 mins. to a stirred solution of phthalid-3-yl D-aaminophenyl-acetamidopenicillanate (5 m. mole) and N,N dicyqlohexylcarbodi-imide (5.8 m mole) at 0C in dry methylene dichloride.

After stirring at 0C for 30 mins. and 1% hours at ambient temperatures, the mixture was cooled to l0C and the dicyclohexylurea removed by filtration.

The solution was washed with dilute hydrochloric acid (pH 1.5), water, and'brine and the dried solution concentration to low volume in vacuo to induce crystallisation. The filtered solid was dried under vacuum over phosphorus pentoxide.

METHOD B Ureido- (or substituted-ureido-) acid (0.01 mole) in dry acetone ml) at 10C was treated with triethylamine (ca. 0.015 mole) and iso-butylchloroformate (0.01 mole) and stirred at l0C for not more than 30 mins. D-a-aminophenylacetamidopenicillanic acid, trihydrate (0.01 mole) in water (60 ml) was treated with triethylamine to give a clear solution (pH 8.4). Acetone (60 ml) was added and the solution cooled to 0C.

The mixed anhydride solution cooled to 40C was filtered through Celite into the stirred penicillin solution and the mixture allowed to warm slowly to room temperature over 20 mins.

The acetone was evaporated in vacuo and the aqueous residue washed well with ether and then acidified to pH2 under a layer of ethyl acetate with 5N hydrochloric acid.

The product is obtained either as the free acid by filtration of the aqueous/ethyl acetate mixture or by precipitation from the ethyl acetate solution with potassium or sodium 2-ethylhexoate to give the corresponding alkali-metal salt.

Method Bi As B, but using N-methylmorpholine instead of triethylamine in the preparation of the mixed anhydride.

Method Bii As B, but using D-a-amino-(p-hydroxyphenyl- )acetamidopenicillanic acid, trihydrate instead of D-aaminophenylacetamidopenicillanic acid, trihydrate.

Method Biii As (Bii) but using N-methylmorpholine instead of triethylamine in the preparation of the mixed anhydride.

Method Biv As (Bi), but using D-a-amino-(3-thienyl)- acetamidopenicillanic acid instead of D-a-aminophenylacetamidopenicillanic acid, trihydrate.

Method Bv As (Bi), but using D-a-amino-(1,4-cyclohexadienyl- )acetamidopenicillanic acid instead of D-oz-aminophenylacetamidopenicillanic acid, trihydrate.

Method Bvi As (Bi), but using ethylchloroformate instead of isobutyl chloroformate and D-a-aminocyclopropylacetamidopenicillanic acid, trihydrate.

Method. Bvii As (Bi), but using D-a-aminovalerarnidopenicillanic acid instead of D-a-aminophenylacetamidopenicillanic acid, trihydrate.

Method Bviii As (Bi), but using ethylchloroformate instead of isobutyl chloroformate, and D-a-amino-(Z-thienyD- acetamidopenicillanic acid instead of D-a-aminophenylacetamidopenicillanic acid, trihydrate.

Method Bix As (Bi), but using D-a-amino-B-phenylpropionamidopenicillanic acid instead of D-a-aminophenylacetamidopenicillanic acid.

(NO METHOD C) METHOD D 8 METHOD E Anhydrous D-a-aminophenylacetamidopenicillanic acid (5m. mole) in dry methylene dichloride (50 ml) was treated with triethylamine (-10 m. mole) to give a clear solution. Trimethylsilyl chloride (10 m. mole) was added and the mixture refluxed under nitrogen for 1 hour, then cooled to 0C.

a-Guanidino-acid (5 m. mole) was dissolved in dry dimethylformamide (5 ml) and dry dimethylformamide (5ml.) and dry methylene dichloride (50 ml) added, cooled to 0C and stirred for 5 mins. with dicyclohexylcarbodi-imide (5.5 m. mole). The bis-trimethylsilylated penicillin was added and stirred at 0C for 1 hour. The mixture was then cooled to 20C and the dicyclohexylurea removed by filtration. The filtrate was evaporated to dryness in vacuo and the residue dissolved in acetone (20ml)/water (20 ml) and the pH adjusted to 2.5 with 5N hydrochloric acid. After stirring at pH 2.5 for 25 mins. the acetone was removed in vacuo and any solid filtered off. The residual aqueous solution was freeze dried and the resultant solid treated with water at pH 2. The product was filtered and dried.

METHOD F Dicyclohexylcarbodi-imide (5.5 m. mole) was added to a stirred solution of N-substituted-amino acid (5 m. mole) in dry acetone (20 ml) at 0C. The mixture was stirred for 15 mins. at 05C and then left in the refrigerator overnight.

D-a-Aminophenylacetamidopenicillanic acid, trihydrate (5m. mole) was dissolved in acetone (10 ml)/water (10 ml) with triethylamine (0.7 ml) and the hydroxysuccinimide ester filtered in, through Celite. After stirring for 45 mins. the acetone was removed in vacuo, leaving a gelatinous mass. Acidification with 5N hydrochloric acid in aqueous ethyl acetate gave the product as the free acid (sometimes only after concentration of the ethyl acetate layer and treatment with ether) or as the salt by treatment of the washed and dried ethyl acetate layer with sodium or potassium 2-ethyl hexoate.

Method Fi As F, but the hydroxysuccinimide ester formed in dry dimethylformamide (or dimethylformamide diluted with. acetone).

Method Fii As F, but the hydroxysuccinimide ester formed in dry 1,2-dimethoxyethane.

Method Fiii As (Fi), but the penicillin dissolved in acetone/- chloroform, the product coming out of solution as the amine salt.

EXAMPLE 1 D-a-[D-B-(p-l-lydroxyphenyl)-a-ureidopropionamido]phenylacetamido penicillanic acid (R Ph; R -pHOPhCH R H; R NHCONH M H; a =D). Prepared by method (Bi), from D-B-(p-Hydroxyphenyl)-a-ureidopropionic acid.

Yield: 68%.

vmax (KBr): 3350, 1770, 1650, 1515, 1230 and 8[(CD SO]: 1.44 (3H.s.gem methyl); 1.57 (3H. s. gem methyl); -2.8 (2H. m. Q CH 4.29 (1H.s. C-3 proton); -4.5 (ll-1 m. g ll CH 5.35-5.87 (5H. m. B-lactams, Ph C NHCONHJ) 6.27 (1H. cl. NliCONI-lf); 6.67

33 34 We claim: 3. A penicillin of claim 1 wherein the carbon atom 1. A penicillin of formula (I): attached to R is in the D-configuration.

R-CH-CO-NH I i S 3 NH N CH3 (1) C 1 l 2 0 COOH R CH C R wherein 4. A penicillin of claim 1 wherein R is phenyl, 4-

R is phenyl, hydroxyphenyl, halophenyl, nitrophenyl, hydroxyphenyl or 3-thienyl.

alkoxyphenyl having [-3 carbon atoms in the alk- 5. A penicillin of claim 1 wherein R is 2-thienyl. xy p r ph y r 3- nyl, y alkyl 6. A penicillin of claim 1 wherein R is 3-thienyl.

having 3-7 carbon atoms in the cycle part, cy- 7. A penicillin of claim 1 wherein R is indol-3'yl.

loalk nyl having -7 c r n a om in the cycl 8. A penicillin of claim 1 wherein R is ll-l-imidazolpart, or alkyl having l-4 carbon atoms; 5- l is y 'y 'Y 9. A penicillin of claim 1 wherein R is hydrogen. R2 is 10. A penicillin of claim 1 wherein, when R is (ll), R is amino or hydrogen or, when R is (III), R is *NH Ti 11' f 1 1 h m t 5 a penici in o cairn w erem c es er IS fi (m or C R phthalidyl, 5,6-dimethoxyphthalidyl, pivaloylox- 0 ymethyl or acetoxymethyl.

12. A penicillin of claim 1 wherein the salt is a base in which R is amino, monoor di-alkylamino having addition acid addition saitcarbon atoms in the alkyl part, cyclohexyp 13. The compound of claim 1 which is 6(D,a-[D,aamino, hydrogen,-alkyl or l-4 carbon atoms or i -fi-( y PTOPiOIiamidO] phehyiacetamido) phenyl, and R is amino, monoor di-alkylamino Pehiciiiahic acidhaving 1-4 carbon atoms in the alkyl part or cyclo- The compoiihd of claim 1 which is i iaformamido-fl-(3-indolyl)propionamido]- hexylamino; R is hydrogen or alkyl of l-3 carbon atoms; or a Phehyiaceiamido) Peniciiiahic acidpharmaceutically acceptable salt or a pharmaceuti- The compofihd of fiiaiih which is iB' cally acceptable hydrolyzable ester which converts i h f p l'p y to the free acid form in vivo. 40 Pheiiiciiiahic acid- 2. A penicillin of claim 1 wherein the carbon atom attached to R is in the D-configuration.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT N0. 3,923,788 Q DATED December 2, 1975 g 1 of 3 ENVENTOR) 2 Harry Ferres et a1 it is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading the assignee should read -Beecham Group Limited, England-;

Column 2, line 18 "cyclophexylamino" should read ---cyclohexylamino--;

Column 5, line 27 "0RGAN-" should read --organline 28 "ISMS" should read --isms-;

k 2 line 41 "oof" should read --of--; g

Column 15, line 49 "-P-" should read -p- Column 17, line 66 '-'D-a-[D-aFormamido" should read 6 --D-a-[D-a-Formamido--;

Column 19, line 42 "penicillinate" should read --penicilla.nate--;

Q Column 22, line 57 "D-a-[-u-METHYL-aUREIDOPROPIONAMIDO]- should read -D-a-[-a-METHYL'-a- UREIDOPROPIONAMIDOl- Column 23, line 63 "PIONAMIDElPI-IENYLACETAMIDO" should read --PIONAMIDO]PHENYLACETAMIDO--;

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTEQN PATENT NO. 3,923,788 Q DATED December 2, 1975 |NVENTQR(5) Harry Ferres et a].

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 23, line 67 "a Ureido-L-IS- (p Me-" should read --o-Ureido-L5- (pMea Column 24, line 15 "D-d-[D-aGUANIDINO-IS-PHHYLPRO-" should read D-a-[D-m-GUANIDINO-B- PHENYLPRO- line 17 "PENICLLANIC" should read --PENICILLANIC-;

Column 25, line 9 "PENICILLINATE" should read --PENICILLANATE--;

Column 26, line 49 "P-PHENYL-PRO-"' should read -p-PHENYL-PRO- Column 27, line' 55 "PHENYIACETAMIDOPENICILLANATE-" should read --PHENYLACETAMIDOPENICILL- ANATE--;

line 56 Delete "PHENYLACETAMIDOPENICILLANATE" which is a duplicate of the preceding line;

Column 28, line 64 "(M-HYDROXYPHENYL)" should read (m-HYDROXYPHENYL) 

1. A PENICILLIN OF FORMULA (I):
 2. A penicillin of claim 1 wherein the carbon atom attached to R is in the D-configuration.
 3. A penicillin of claim 1 wherein the carbon atom attached to R2 is in the D-configurAtion.
 4. A penicillin of claim 1 wherein R is phenyl, 4-hydroxyphenyl or 3-thienyl.
 5. A penicillin of claim 1 wherein R1 is 2-thienyl.
 6. A penicillin of claim 1 wherein R1 is 3-thienyl.
 7. A penicillin of claim 1 wherein R1 is indol-3-yl.
 8. A penicillin of claim 1 wherein R1 is 1H-imidazol-5-yl.
 9. A penicillin of claim 1 wherein R3 is hydrogen.
 10. A penicillin of claim 1 wherein, when R2 is (II), R5 is amino or hydrogen or, when R2 is (III), R6 is amino.
 11. A penicillin of claim 1 wherein the ester is phthalidyl, 5, 6-dimethoxyphthalidyl, pivaloyloxymethyl or acetoxymethyl.
 12. A penicillin of claim 1 wherein the salt is a base addition or acid addition salt.
 13. The compound of claim 1 which is 6(D, Alpha -(D, Alpha -ureido- Beta -(3-indolyl) propionamido) phenylacetamido) penicillanic acid.
 14. The compound of claim 1 which is 6(D, Alpha -(D,L, Alpha -formamido- Beta -(3-indolyl)propionamido)phenylacetamido) penicillanic acid.
 15. The compound of claim 1 which is D- Alpha -(D,L, Beta -(2-thienyl)- Alpha -ureidopropionamido)-phenylacetamidophenicillanic acid. 